Tesla is opening the doors to its ‘gigafactory’ on July 29

Tesla will open its massive battery “gigafactory” to the general public on July 29.

The company will host a grand opening event attended by, among others, owners who won tickets by participating in its most recent referral program. Those new owners are also helping spread the word in the absence of an official public announcement from Tesla.

Contest winners received their invitations late Thursday and quickly began posting them to social media. A full copy of the emailed gigafactory invitation posted by a “Kushari” soon made its way to Tesla enthusiast site Teslarati. The short letter notes the July 29 date of the grand opening and includes some travel information, but no further details.

An “official invitation” will be emailed to attendees in a few weeks, the letter says.

Referral-program participants won their tickets to the gigafactory grand opening by referring five or more new Model S customers between November 1 and December 31.

Aside from brief visits by a handful of media outlets, few outsiders have seen the gigafactory up close. The factory is crucial to Tesla’s goal of selling the 215-mile Model 3 at a base price of $35,000 (before federal, state, and local incentives). Such a large factory is needed to produce lithium-ion battery cells cheaply enough to achieve that price.

The gigafactory is already building some battery packs for stationary energy storage, but it isn’t fabricating the cells inside them.

Drone footage taken earlier this year showed a largely completed building, painted in Tesla’s signature white with red accents. Throughout the construction process, analysts have debated whether the gigafactory will be completed on time and whether it will really be able to deliver the promised savings on cells when it’s finished.

Tesla must meet certain targets in order to get the full $1 billion in tax incentives offered to it by the Nevada state government over a 20-year period.

In the shorter term, Tesla must ensure that the gigafactory can actually produce the battery cells required for volume production of battery packs for the Model 3.

The company already has somewhere north of 300,000 preorders for the car, which is expected to begin production sometime next year. Tesla now says it expects to build 500,000 cars per year by 2018, rather than 2020, as previously stated. That’s 10 times the number of cars it built last year.

This story originally appeared on Green Car Reports. Copyright 2016